ASME TR A17.1-8.4:2020 pdf download.Guide for Elevator Seismic Design.
The resulting equations indicate that to obtain similarly sized components, the IBC/NBCC SD-based seismic force would need to equal the ASME A17.1/CSA B44 ASD-based seismic force.
The IBC/NBCC seismic force equations can be written in terms of their geographically defined spectral response acceleration values, S and S. respectively. By equating these formulas to a known ASME A17.1/CSA B44 seismic zone level force, the value of Sc and Sa(O.2) that would equal the ASME A17.1/CSA B44 force can be determined. Any S or S(0.2) that exceeds that value on the IBC contour maps or the NBCC 2005 seismic data tables would indicate locations where larger force levels and more robust elevator designs would be required.
The largest expected difference between ASME A 17.1/ CSA B44and IBC/NBCC force levels was forguide rails/rail brackets at the upper portion of the building, due to the introduction of the amplification factor in IBC/NBCC force equations. Because of their dependence on component height placement in the building, IBC/NBCC forces at the top of the building would be up to 1.6 times greater than at the building base. When compared to height-invariant ASME A17.1/CSA B44 rail bracket forces, the force levels required by IBC/NBCC at the top of the building were expected to generate design changes for a large portion of the U.S. and Canada. The comparison of IBC/NBCC force levels and ASME A17.1/ CSA B44 seismic zone 3 guide rail force levels is detailed in Table 1-3.1.3-1. The comparison in Table 1-3.1.3-1 of ASMEA17.1/CSAB44zone3andlBC/NBCC2OlOforcesis taken at the top of a building. Due to the height variable in the IBC (z) and NBCC (Iii) seismic force equation, IBC and NBCC forces in the center and lower portions of the building will be reduced. Therefore, the impact of changing to IBC and NBCC forces should be greatly reduced in the mid to lower half of buildings.
Table 1-3.1.3-2 indicates the impact of the introduction of IBC/NBCC 2005 (and later editions) seismic force levels for a building in the U.S. and Canada. The chart indicates that for the upper half of a building, in areas where ASME A17.1/CSA B44 zone 3 requires only O.5g seismic forces (such as rail brackets), seismic forces will increase for some portions of the country. Other locations within the building will see little to no increase above ASME A17.1/CSA B44 seismic zone force levels.
1-4 USING IBC/ASCE 7 FOR ELEVATOR SEISMIC DESIGN (QUICK REFERENCE)
By obtaining the following IBC parameters, the need for elevator seismic design and required seismic force levels can be determined:
(a) Seismic Design Category (SDC)
(c) SDS
(d) location of the base of the building
(e) average roof height of the building
For quick reference, Table 1-4-1 compares the horizontal force generated by the IBC parameters (at the worst-case height ratio) and the equivalent seismic zone(s) force(s).
1-5 SUMMARY
While at times requiring slightly increased seismic force levels in the upper half of the building, particularly in the area of rail bracket selection and spacing, adoption of the IBC/NBCC seismic force levels might result in less-stringent seismic forces in the lower half of the building than are currently required byASME Al 7.l/CSA B44. Use of IBC contour maps and the NBCC seismic data chart may introduce seismic requirements in areas that had been traditionally nonseismic. Regardless of the changes these force levels will dictate, the benefits of clarity in the code and use of the latest and most accurate information in seismic force protection are warranted.ASME TR A pdf download.